2 FreeRTOS V9.0.1 - Copyright (C) 2017 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.
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13 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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73 + pxPortInitialiseStack() now initialises the stack of new tasks to the
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74 same format used by the compiler. This allows the compiler generated
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75 interrupt mechanism to be used for context switches.
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77 Changes from V2.4.2:
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79 + pvPortMalloc and vPortFree have been removed. The projects now use
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80 the definitions from the source/portable/MemMang directory.
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82 Changes from V2.6.1:
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84 + usPortCheckFreeStackSpace() has been moved to tasks.c.
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90 #include "FreeRTOS.h"
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92 /*-----------------------------------------------------------*/
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94 /* See header file for description. */
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95 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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97 StackType_t DS_Reg = 0, *pxOriginalSP;
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99 /* Place a few bytes of known values on the bottom of the stack.
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100 This is just useful for debugging. */
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102 *pxTopOfStack = 0x1111;
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104 *pxTopOfStack = 0x2222;
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106 *pxTopOfStack = 0x3333;
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108 *pxTopOfStack = 0x4444;
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110 *pxTopOfStack = 0x5555;
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114 /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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116 /* We are going to start the scheduler using a return from interrupt
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117 instruction to load the program counter, so first there would be the
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118 status register and interrupt return address. We make this the start
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120 *pxTopOfStack = portINITIAL_SW;
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122 *pxTopOfStack = FP_SEG( pxCode );
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124 *pxTopOfStack = FP_OFF( pxCode );
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127 /* We are going to setup the stack for the new task to look like
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128 the stack frame was setup by a compiler generated ISR. We need to know
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129 the address of the existing stack top to place in the SP register within
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130 the stack frame. pxOriginalSP holds SP before (simulated) pusha was
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132 pxOriginalSP = pxTopOfStack;
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134 /* The remaining registers would be pushed on the stack by our context
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135 switch function. These are loaded with values simply to make debugging
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137 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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139 *pxTopOfStack = ( StackType_t ) 0xCCCC; /* CX */
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141 *pxTopOfStack = FP_SEG( pvParameters ); /* DX */
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143 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BX */
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145 *pxTopOfStack = FP_OFF( pxOriginalSP ); /* SP */
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147 *pxTopOfStack = ( StackType_t ) 0xBBBB; /* BP */
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149 *pxTopOfStack = ( StackType_t ) 0x0123; /* SI */
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151 *pxTopOfStack = ( StackType_t ) 0xDDDD; /* DI */
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153 /* We need the true data segment. */
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154 __asm{ MOV DS_Reg, DS };
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157 *pxTopOfStack = DS_Reg; /* DS */
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160 *pxTopOfStack = ( StackType_t ) 0xEEEE; /* ES */
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162 /* The AX register is pushed again twice - don't know why. */
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164 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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166 *pxTopOfStack = FP_OFF( pvParameters ); /* AX */
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170 /* The compiler adds space to each ISR stack if building to
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171 include debug information. Presumably this is used by the
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172 debugger - we don't need to initialise it to anything just
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173 make sure it is there. */
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177 /*lint +e950 +e611 +e923 */
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179 return pxTopOfStack;
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181 /*-----------------------------------------------------------*/
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